There was no warning of the giant waves which struck at Saturday night, destroying hundreds of buildings, sweeping away cars and uprooting trees

It is thought undersea landslides from the Anak Krakatau volcano caused them. Rescue efforts are being hampered by blocked roads

At least 220 people have been killed and 843 injured after a tsunami hit coastal towns on Indonesia's Sunda Strait government officials say. There was no warning of the giant waves which struck at Saturday night, destroying hundreds of buildings, sweeping away cars and uprooting trees.

It is thought undersea landslides from the Anak Krakatau volcano caused them. President Joko Widodo has expressed his sorrow for the victims and urged people to be patient. Rescue efforts are being hampered by blocked roads but heavy lifting equipment is being transported to badly hit areas to help search for victims.

The Sunda Strait, between the islands of Java and Sumatra, connects the Java Sea to the Indian Ocean.

The disaster management agency has warned people to stay away from the coastline due to fears of another tsunami. Saturday's tsunami struck at about 21:30 local time (14:30 GMT), during a local holiday. It hit several popular tourist destinations including the Tanjung Lesung beach resort in the west of Java island.

Footage shared on social media showed a large wave crashing into a tent in the resort, in which popular Indonesian rock band Seventeen was performing. Members of the band were seen being swept away as the wave destroyed the stage.

In a tearful Instagram video, singer Riefian Fajarsyah said the band's bassist and road manager had died, and three other band members and his own wife were missing.

It appears that the main road into Pandeglang has been badly damaged, making it difficult for rescuers to reach the area, she added. Eyewitness Asep Perangkat said cars and containers had been dragged about 10 meters.

Buildings on the edge of [Carita] beach were destroyed, trees and electricity poles fell to the ground, he told AFP news agency.

Officials say more than 160 people were killed in Pandeglang - a popular tourist district on Java known for its beaches and national park. Meanwhile, 48 were reported dead in South Lampung on Sumatra, and deaths were also reported in Serang district and Tanggamus on Sumatra. Officials fear the death toll could rise further.

Anak Krakatau has seen increased activity in recent months. Indonesia's geological agency says the volcano erupted for two minutes and 12 seconds on Friday, creating an ash cloud that rose 400 meters above the mountain. It recommended that no-one be allowed within 2km of the crater.

After the tsunami struck, there was confusion over what had actually happened, with Indonesian disaster agency spokesman Sutopo Purwo Nugroho initially reporting it as a tidal surge. He later apologized for his mistake, saying there had been confusion because there was no earthquake.

Anak Krakatau (Child of Krakatau) is a new island that emerged in 1927 from Krakatoa volcano. In August 1883, Krakatoa underwent one of the most violent volcanic eruptions in recorded history: The eruptions were equivalent to 200 megatons of TNT - about 13,000 times the nuclear yield of the bomb dropped on Hiroshima in 1945.